the head should always tilt a little to the left because the left hand is higher so that's a more relaxed position.

the samurai position is probably only relevant for service returns for 2hbh players who have the 2 hands close together.....and for some players at the net.

actually even for volleys the samurai position is not ideal..... the contact point for the bh volley is more forward than the fh volley, so you have less time on the bh side, therefore the ready position should favor the bh volley also.

When playing the net, the ready position in the top photo in the OP is ideal. At the baseline, the ready position is much less critical. I encourage students to adopt the ready position shown in that photo so that they already have developed the habit for net play. This ready position creates a mild extension of the wrist -- it should not be too stressed since the upper hand should really be supporting the weight of the racket (so as to keep the lower hand/arm fairly relaxed). This mild extension should facilitate the much greater wrist extension needed for FH volleys. The wrist will assume a more neutral position for a BH volley.

Shouldn't draw too many conclusions from an informal practice session. Some of his volleys & movement are a bit sloppy here. There are plenty of videos of Roger warming up where he does not employ knee bend. In actual play, Roger may have his racket slightly skewed for his "ready" at the net. It is certainly not the "ready" shown in the 2nd image in the OP.

Roger reads the ball much better than the rest of us. He also has world class reflexes that few possess. He would not have much trouble getting his racket on the ball from any ready position. Not true for us mere mortals.

When I hit my FH volleys, my contact point is pretty much forward (nearly even with my front shoulder, not my rear shoulder). I do not have much difference, if any, between the contact point for most of my FH and BH volleys. Regardless of the CP, the limiting factor is actually how much time it takes to get the racket around and the wrist laid back for the FH.

My hand moves forward a bit as I turn to line up the ball for either a FH or BH volley. Not much wrist extension for the BH volley at all. I can quickly pivot the racket to set up for the BH -- much quicker than for the FH. This is why I advocate a neutral racket orientation for the "ready" at the net.

^ Nobody? Again, Paes, Bhupathi and the Bryan bros can read the ball extremely well and all have superior reflexes (perhaps even better than Roger). A slightly skewed "ready" may be fine for them but perhaps less so for many lesser players with non-elite skills/reflexes. Note that none of the players in the vid use the significant/exaggerated skew shown in the 2nd image in the OP.

I do not have much trouble at all hitting a 1-handed BH volleys with balls at my chest. I can move the racket to that position quicker than getting the racket around for the forehand volley. I've seen many others with the same issue. It could bery well be an individual thing.

Note: I have fairly long arms and I find that internal (shoulder) rotation is much quicker than external rotation. I find that the neutral racket orientation is optimal at the net. For quite a few years I had the racket orientation slightly offset (skewed) but discovered that this was not optimal for me at the net. When playing doubs, I find the neutral position works best in most situations.
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Personally, I don't believe in the balanced ready position for serves OR groundies.
We all have one side that is slower to prepare, or takes more preparation to hit, so we need to favor that side.
Like me, I'm a little slow on my backhand volleys, and that stroke takes a longer prep and backswing, so I always prep favoring that side.

One of the myths of the ready position, is to hold the racquet straight forward in front of your body. This should only occur, when you are in the ready position holding your racquet with your eastern forehand grip or if you have a two handed backhand .

If you choose to hold the racquet with a backhand grip, either anticipating a backhand or just because it feels right, then your racquet should lay parallel to your body.